Field of the Invention
The present invention relates to a laundry machine, and, more particularly, to a laundry machine capable of generating steam, to use the steam, and a control method of the same.
Discussion of the Related Art
A laundry machine may include a washer and a dryer. Here, the washer means an apparatus for separating contaminants from laundry, using wash water and detergent. That is, the laundry machine may separate contaminants from laundry by utilizing chemical action of detergent dissolved in wash water and mechanical action of wash water or mechanical action by driving of an inner tub (drum).
The dryer means an apparatus for drying laundry. That is, the dryer dries laundry by supplying hot dry air to the laundry.
Another laundry machine may include a combination washer and dryer capable of not only performing drying, but also performing washing. Similarly to the above-mentioned laundry machine, the combination washer and dryer may perform washing, using wash water and detergent. In this regard, the combination washer and dryer may be referred to as a laundry machine.
One type of laundry machine is a horizontal-axis laundry machine in which a drum receiving laundry is driven with respect to a horizontal axis, to perform washing. In such a horizontal-axis laundry machine, mechanical energy is applied to laundry through driving of the drum, to separate contaminants from the laundry.
The washing environment of the horizontal-axis laundry machine may be an environment in which laundry is partially immersed in water. Accordingly, most mechanical actions to wash laundry in the horizontal-axis laundry machine may include friction among clothes of laundry, friction between the laundry and the drum, impact force applied to the laundry, etc. Of course, in this case, washing may be carried out through chemical action of a detergent.
Another type of laundry machine is a vertical-axis laundry machine in which an inner tub receiving laundry rotates with respect to a vertical axis, or a pulsator installed in the inner tub rotates, to perform washing. In such a vertical-axis laundry machine, mechanical energy is applied to laundry through driving of the inner tub or pulsator, to separate contaminants from the laundry, as in the above-mentioned horizontal-axis laundry machine.
The washing environment of the vertical-axis laundry machine may be an environment in which laundry is partially immersed in water. Accordingly, most mechanical actions to wash laundry in the vertical-axis laundry machine may include friction between the laundry and the flow of water, impact force applied to the laundry, etc. Of course, in this case, washing may also be carried out through chemical action of a detergent.
Thus, the vertical-axis laundry machine and horizontal-axis laundry machine have a great difference in terms of amount of wash water used in washing and washing mechanism.
In spite of such a difference, both the horizontal-axis laundry machine and the vertical-axis laundry machine may include a washing heater for heating wash water. Heating of wash water may be carried out for promoted activation of detergent to obtain enhanced washing effects and for enhanced sterilization effects at high temperature. Therefore, generally, the temperature of wash water may be increased to a predetermined temperature through driving of the washing heater. That is, generally, washing effects may be enhanced through an increase in the temperature of wash water.
Recently, a laundry machine, in which steam is supplied to create a high-temperature washing environment while reducing energy consumption, has come into wide use. In such a laundry machine, steam is generated and supplied to a drum in order to create a hot and humid washing environment for enhanced washing effects. This laundry machine may obtain enhanced washing effects through a steam washing course using steam in addition to water washing.
In such a laundry machine, however, there are increased costs and control difficulty because a separate steam generator should be employed. In detail, the steam generator includes a steam heater for generating steam, separately from a general washing heater. For this reason, use of a laundry machine, which employs a washing heater while excluding a separate steam generator, has been proposed.
Steam may be generated through heating of water to the boiling point of water or above. In this regard, a laundry machine equipped with a separate steam generator may be a laundry machine in which water is heated to the boiling point thereof or above, to generate steam, and the generated steam is used for washing. Steam may also be generated through heating of water to a temperature lower than the boiling point of water. In this regard, a laundry machine, which employs a washing heater while excluding a separate steam generator, may be a laundry machine in which water is heated to a temperature lower than the boiling point thereof, to generate steam, and the generated steam is used for washing.
In the laundry machine, which generates steam, using the washing heater, steam is generated within the tub. That is, steam may be generated in a relatively large space. Therefore, generally, steam may be generated through heating of water to a temperature lower than the boiling point of water by the washing heater.
In the laundry machine, which generates steam, using the washing heater, steam is mainly used during water washing due to structural restriction.
Steam may be used to obtain enhanced washing effects in water washing. Steam may also be used to refresh laundry. In particular, in a laundry machine such as a dryer, a refreshing course may be provided.
In a dryer, steam may be mainly used to refresh laundry, for example, to remove creases or odor, rather than for enhancement in washing effects.
Hereinafter, a conventional general laundry machine will be described with reference to FIGS. 1 and 2.
The laundry machine may include a cabinet 10 to form an appearance of the laundry machine, and a tub 20 installed in the cabinet 10. The tub 20 may be configured to receive wash water.
The tub 20 may be provided with a washing heater 60 for heating wash water. Due to gravity, the water level of wash water supplied to the tub 20 may be gradually increased from a bottom surface of the tub 20. Accordingly, the washing heater 60 may be arranged at a lowest portion of the tub 20.
A drum 30 is disposed within the tub 20. The drum 30 is rotatably installed in the tub 20. Laundry is received in the drum 30. The drum 30 may be driven by a driving unit 71-72. Through driving of the drum 30, washing may be carried out.
The driving unit may include a motor 71. Driving of the motor 71 may be directly converted into driving of the drum 30. Such a structure is generally referred to as a “direct connection type motor structure. Of course, rotation of the motor 71 may be converted into driving of the drum 30 via a pulley 72, as illustrated in the drawings.
Due to driving of the drum 30, etc., vibration may be transmitted to the tub 20. To this end, the tub 20 may be supported with respect to the cabinet 10 by dampers 21.
A door 40 may be provided in front of the drum 30. A gasket 50 may be provided in rear of the door 40. The gasket 50 may be connected to the cabinet 10 and tub 20. Accordingly, the front side of the tub 20 may be elastically supported with respect to the cabinet 10 by the gasket 50.
For execution of washing, wash water should first be supplied. To this end, a water supply unit 80 is provided to supply wash water from an external water supply source to the laundry machine.
The water supply unit 80 may include a water supply valve 81, which is selectively opened or closed, and a wash water passage 82. The wash water passage 82 may be connected with a detergent box 83 for receiving detergent. The detergent box 83 may be supplied to a supply passage 84. Wash water and detergent supplied through the supply passage 84 may be mainly supplied to the interior of the drum 30.
As illustrated in FIG. 2, a plurality of through holes 31 is provided at the drum 30. The interior of the drum 30 may communicate with the interior of the tub 20 through the through holes 31.
A heater mounting recess 22 may be formed at a lower portion of the tub 20. The heater mounting recess 22 may be provided at a lowermost portion of the tub 20. Since the washing heater 60 is mounted in the heater mounting recess 22, it may remain immersed in water even at a lowest level of wash water.
The heater mounting recess 22 may be connected to a drainage passage 23. Accordingly, wash water in the tub 20 may be drained outwards of the laundry machine via the heater mounting recess 22 and drainage passage 23.
As mentioned above, generally, generation of steam using the washing heater 60 requires water washing as a precondition thereof. This may also be seen from the structural features of the laundry machine illustrated in FIGS. 1 and 2.
In detail, wash water and detergent for washing are supplied to the interior of the drum 30. That is, when supply of water is executed, the supplied wash water and detergent wet laundry received in the drum 30. The wash water and detergent is partially collected in the tub 20, starting from the bottom of the tub 20.
As supply of water continues, the level of wash water is gradually increased. Supply of water continues until the level of wash water reaches a predetermined water level.
In particular, the predetermined water level in the horizontal-axis laundry machine is relatively lower than that of the vertical-axis laundry machine. In other words, in the horizontal-axis laundry machine, washing is carried out in an environment in which laundry is partially immersed in water. Therefore, the structure in which wash water and detergent are directly supplied to laundry may be general.
In order to generate steam, using the washing heater, accordingly, there may be a problem in that water should always be supplied through the interior of the drum. That is, there may be a problem in that supply of wash water inevitably involves wetting of at least a portion of the laundry received in the drum.
For this reason, there is difficulty in variously utilizing steam because utilization of steam requires water washing as a precondition thereof. In detail, there are many problems in utilizing steam only for refreshing. This is because laundry to be refreshed has a very high moisture content due to the above-mentioned structural problem and, as such, a separate drying procedure should be needed.
Meanwhile, the level of refreshing in conventional laundry machines is about a level of simply supplying moisture to laundry, using steam. That is, refreshing in conventional laundry machines only involves tumbling in the drum in order to uniformly supply steam to all laundry. Therefore, it is necessary to provide a scheme capable of deriving optimal relations among the steam generation and supply structure, the temperature of steam, and driving of the drum, to enable execution of more effective refreshing.
In addition, it is necessary to provide a laundry machine capable of performing refreshing while reducing a subsequent drying procedure as much as possible. That is, it is necessary to provide a laundry machine capable of realizing a refreshing performance enabling wearing of clothes just after refreshing thereof without requiring drying through a dryer or natural drying.